Sailing boat handling- 'Back and fill' using prop-walk
by John Jamieson on 22 Feb 2013
This one is for the first time owner of a sailing boat: You enter a narrow canal that leads to a marina when all of a sudden, you need to turn around 90° or more inside a space just a bit longer than the length of your sailing boat! How can you do this?
Determining your 'prop-walk'
It’s getting narrow - Looking ahead, would you be able to turn in your own length if you had to? .. .
First you need to determine whether your boat has a right- or left-handed screw. Most single screw boats have right-handed screws, but you must be sure of this before you can master boat handling.
Imagine that you are able to stand behind your boat and watch her propeller. Your sailing partner stays aboard at the controls. As soon as your sailing partner places the shifter into idle ahead propulsion, note the direction of rotation of the screw. If the propeller rotates to the right in ahead propulsion, you have a right-hand propeller (also called a 'right-hand screw'); if it rotates to the left in ahead propulsion, you have a left-handed propeller (also called a 'left-hand screw').
Note also that the stern of the boat will tend to 'walk' in the direction of rotation. Let's discuss just right-handed props because most boats have these installed. In ahead propulsion with the rudder centered, our right-handed prop rotates to the right. The stern of the boat will 'walk' in this direction and the bow of the boat will move in the opposite direction. Now let's see what happens in reverse propulsion...
If your sailing partner shifts into reverse propulsion, the right-handed screw would rotate in the opposite direction, or to the left. The stern of the boat will 'walk' to the left and the bow will move in the opposite direction. Confirm what 'hand' of prop your sailboat has with a simple test. In an open area, shift your engine into idle reverse propulsion. Remember that a right-hand screw walks to the left when you are in reverse (a left-hand screw will walk to the right when you are in reverse).
How to turn a tight situation:
Let's say we are aboard a sailboat with a right-hand screw. We need to turn 90° to the right inside a narrow canal with space just a bit more than the length of our boat. We first move over near the left side of the narrow canal.
Use a technique called 'backing and filling' to pivot your boat in a tight circle. Hold the wheel hard over to the right (or tiller hard over to the left) throughout the maneuver. Do not move the wheel or tiller (Illustration Step 1)
Next, give a short burst (about one second) of forward propulsion. Shift into neutral for one second. Then, give a short burst of reverse propulsion (about one second). Shift into neutral for one second. Continue this sequence (Illustrations Step 2 and Step 3).
Each time you give a short burst of forward propulsion, powerful discharge current strikes the rudder blade and causes the bow to pivot to the right (and the stern to pivot to the left). Our objective will be to stay in one spot without surging ahead; so take care not to leave the shifter in gear too long.
Then, shift into neutral for about one second. Next, shift into reverse propulsion and give a short powerful burst of about one second. This forces the discharge current up toward the right side of the hull, stops the forward motion, and forces the stern to 'walk' to port--just what we want when we pivot to starboard (see Illustration).
Practice this maneuver in open areas before you get into a confined space. Learn how your boat reacts in different conditions of wind and current. That way, once you find that you must pivot in a confined space, you will be well prepared to execute this maneuver with confidence.
Don't forget, you will only be able to 'walk the prop' in one direction. So if, in the above case, the required turn is to the left, you can do it quite successfully by turning 270 degrees to the right. Patience is the essence.
John Jamieson (Captain John) with 25+ years of experience shows you the no-nonsense cruising skills you need for safer sailing worldwide. Visit his website at www.skippertips.com. Sign up for the Free, highly popular weekly 'Captain John's Sailing Tip-of-the-Week'. Discover how you can gain instant access to hundreds of sailing articles, videos, and e-Books!
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